Fuel Pump Relay

[wickedfronty]

I have a 1973 240z and it wasn't getting any gas, so I blew the fuel lines and cleaned the tank then I bought a new fuel pump and connected it. My problem is that the pump is not getting enough power. I measured how much electricity the pump is getting and it was only 0.04 volts.

So I traced all the wiring that goes to the pump and I think I found the problem. the wire that I think powers the pump is connected to a relay on the passengers side. the power going in is 11.08 volts but the other three wires that go to or are coming out of the relay only have 0.03 volts.

is this normal?when I test them I have the key on the ON position. how many volts should be coming out of the relay?can anyone tell me where I could buy the relay?

I went to the local parts store but they don't know squat about imports.

any help would be apprecitated

[Xargon321]

the electric fuel pump wont start untill the car is running at 400 rpm and above, get the mechanical pumped checked it might be fubared.

[frank13]

True that. The Electric pump only works at key on for a few seconds for fuel system prime. Then if the the car does not start above four hundred or above rpms (if i remember right through the oil pressure ssending unit) it will not run. Saftey dealie. Check your fuel lines as well from the tank and at all connections. Any leaks, weather the leak or suck air will affect the way the pump(s) do thier jobs correctly! :devious:

[frank13]

is low any relay should get Bat V. Or as close as B+ as possible. You have a bad Voltage drop at your relay or in the connectors. You should have four prongs on your relay. One B+ feed key on. One that grounds the coil side of the relay with the engine cranking above four hundred. One that when that condition is met B+ and the last is the actual Voltage to the pump. The pump is a voltage drop to ground after itself, 4 Prongs, 2 +, 2-. :devious:

[chaztg]

In my 73, I'm using an RX7 fuel pump mounted in the rear in place of the stock auxillary pump (which to my knowledge) is a supplementary pump not rated for enough psi to supply the carbs alone and was only installed in the 73s & 74s to counter the vapor lock problems with the flattop carbs. I read earlier in the thread that the rear mounted electric fuel pump wiring will run only at 400 rpm & above...well, mine runs all the time and it's always been hooked up with the stock wiring (why not, it's already there right?). I'm sure you guys all know about the wiring pigtail with an inline fuse next to the radio, which curiously all 240Zs have the plug (taped to the harness in pre-73 Zs) along with the fuel pump wiring in the rear(...?) This I could never figure out. I guess my question is why do all 240s have the wiring, even though the early cars without the vapor lock issues should never have had a provision for a part that was an engineering solution for future cars only...puzzling.

[rbauwen]

can anyone post a picture of where the fuel relay may be located for a 73 240z

[beermanpete]

There is no relay for the fuel pump in the '73. There is separate fuse for it that is not in the fuse box. Have you check that? It is near the fuse box. You may need to remove the center console to find it.

[zKars]

Whoa, for a minute there I thought I logged onto zcar.com by mistake this morning....